All round improvement

12th IoRW Technical Seminar

Recent Developments in Rail Welding

This seminar focused on the improvements that are constantly being made to rail welding processes and associated equipment. The event was chaired by Bob Sawdon, Balfour Beatty Rail Technologies, and Vice Chairman of the Institute of Rail Welding Management Committee. The level of attendance was excellent and amongst the 90 or so delegates, several were from outside the UK, indicating the wide international interest that IoRW is now attracting.

Robotic welding - a first for Network Rail Track Welding Photo: Andrew Beeson Network Rail

Both of the approved aluminothermic welding (ATW) process suppliers gave an update on their equipment and current activities. Mick Wainright of Thermit Welding (GB) Ltd began by outlining an analysis that has been conducted to better understand the occurrence of rail welding defects, and how this has led to the provision of more information to users and to equipment developments, notably the single use crucible (SUC). This technique has now been accepted by Network Rail. Thermit have also developed an ATW rail head repair technique.

With regard to the other ATW process supplier, Railtech (UK) Ltd, Richard Kyte, Steve Kettle and Nigel Davis gave a joint presentation on equipment improvements. A new 'gas box' has been developed in order to provide better control of joint preheating and it has also been possible to reduce the torch length and weight. A new range of moulds for wide gap and composite welding are currently under development. Railtech also reported trials being conducted in the USA on head repair welding by ATW.

There have also been advances in flash butt welding of rail and Dennis Shears of Holland LP in the USA gave a presentation covering both the technology and the application aspects. Attention has been paid to the mechanism of formation of flat spot defects. This has led to the development of a new technique, the 'Paton pulse process', which allows a considerable decrease in the weld gap during flashing and produces a uniform melt surface. The technique is applied by means of a regulation system which maintains stable flashing at a minimum possible voltage. Data on the improvements obtained with the new technique was presented.

Arc welding was the subject of a presentation by Geoff Chapman of Network Rail, covering the ESAB Railtrac BV/BVR 1000 equipment for fully automatic repair of rail and track components. This equipment is currently one of its type that is approved by Network Rail. The programming unit of the equipment allows the welder to select a variable range of welding sequences and the hand module activates and terminates welding giving the welder the opportunity to make minor adjustments during welding. Current developments include the use of the system on switchblade repair. A second presentation from a speaker from Network Rail followed. Bill Mosley gave a brief update on welding issues. These included: progress towards acceptance of ATW for rail head repair (Thermit and Railtech); approval of the Geismar MP23 grinder; the imminent acceptance of a weld alignment device; and updates to training packages for both ATW and arc welding.

Accidents can still happen, albeit rarely, with gas cylinders. Garry Crace and George Foulger of BOC explained the steps necessary to deal with cylinders in fires. In order to manage the risk, a key requirement is to carry out proper risk assessments which became a legal requirement a year ago.

Joe Small of Jarvis Rail highlighted the importance of rail end preparation on weld quality and stressed the need for proper training and equipment. He reviewed the equipment and techniques available; oxy-fuel gas abrasive disc, band saw, and steel disc; indicating the advantages and disadvantages of each.

The event concluded with a presentation from Jonathon Sanders and Matteo Baracchi of Saint-Gobain Abrasives (SGA) on rail cutting and grinding technology. SGA invest highly in research and development and is active in responding to the rail industry's need for reducing abrasive costs, for example by increasing the life of wheels, and for improving grinding efficiency, for example, by increasing cutting efficiency. The research conducted has led to new product development in wheel materials including a comprehensive testing programme. The new developments have yielded significant performance advantages for customers.

All the presentations are available to IoRW members on this site.

Tim Jessop
Executive Officer